Regulation of hepatic glutamine metabolism by miR-122
| Autor: | Teresa W.-M. Fan, Xiaoli Zhang, Teresa Cassel, Kalpana Ghoshal, Kun-Yu Teng, Vivek Chowdhary, Peng Hu, Dipanwita Sengupta, Mona Aljuhani |
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| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
HSQC heteronuclear single quantum coherence spectroscopy Glutamine Glutaminase activity LKO liver-specific knockout WT wild type Mice 0302 clinical medicine MiR-122 Mice Knockout KO germ-line knockout Chemistry Glutaminase Glc glucose miR-122 3. Good health Liver Gln glutamine Original Article lcsh:Internal medicine Mice Transgenic 030209 endocrinology & metabolism miRNA-122 03 medical and health sciences Downregulation and upregulation Cell Line Tumor Animals Humans Metabolomics lcsh:RC31-1245 Molecular Biology Glutaminolysis SIRM Glu glutamate SIRM stable isotope resolved metabolomics Gluconeogenesis Wild type Cell Biology HCCS Molecular biology MicroRNAs 030104 developmental biology HCC hepatocellular carcinoma Krebs cycle Slc1a5 3′UTR 3′-untranslated region TCGA-LIHC The Cancer Genome Atlas—Liver and Hepatocellular Cancer |
| Zdroj: | Molecular Metabolism Molecular Metabolism, Vol 34, Iss, Pp 174-186 (2020) |
| ISSN: | 2212-8778 |
| DOI: | 10.1016/j.molmet.2020.01.003 |
| Popis: | Objective It is well established that the liver-specific miR-122, a bona fide tumor suppressor, plays a critical role in lipid homeostasis. However, its role, if any, in amino acid metabolism has not been explored. Since glutamine (Gln) is a critical energy and anaplerotic source for mammalian cells, we assessed Gln metabolism in control wild type (WT) mice and miR-122 knockout (KO) mice by stable isotope resolved metabolomics (SIRM) studies. Methods Six-to eight-week-old WT and KO mice and 12- to 15-month-old liver tumor-bearing mice were injected with [U–13C5,15N2]-L-Gln, and polar metabolites from the liver tissues were analyzed by nuclear magnetic resonance (NMR) imaging and ion chromatography-mass spectrometry (IC-MS). Gln-metabolism was also assessed in a Gln-dependent hepatocellular carcinoma (HCC) cell line (EC4). Expressions of glutaminases (Gls and Gls2) were analyzed in mouse livers and human primary HCC samples. Results The results showed that loss of miR-122 promoted glutaminolysis but suppressed gluconeogenesis in mouse livers as evident from the buildup of 13C- and/or 15N-Glu and decrease in glucose-6-phosphate (G6P) levels, respectively, in KO livers. Enhanced glutaminolysis is consistent with the upregulation of expressions of Gls (kidney-type glutaminase) and Slc1a5, a neutral amino acid transporter in KO livers. Both Gls and Slc1a5 were confirmed as direct miR-122 targets by the respective 3′-UTR-driven luciferase assays. Importantly, expressions of Gls and Slc1a5 as well as glutaminase activity were suppressed in a Gln-dependent HCC (EC4) cell line transfected with miR-122 mimic that resulted in decreased 13C-Gln, 13C-á-ketoglutarate, 13C-isocitrate, and 13C-citrate levels. In contrast, 13C-phosphoenolpyruvate and 13C-G6P levels were elevated in cells expressing ectopic miR-122, suggesting enhanced gluconeogenesis. Finally, The Cancer Genome Atlas—Liver Hepatocellular Carcinoma (TCGA-LIHC) database analysis showed that expression of GLS is negatively correlated with miR-122 in primary human HCCs, and the upregulation of GLS RNA is associated with higher tumor grade. More importantly, patients with higher expressions of GLS or SLC1A5 in tumors exhibited poor survival compared with those expressing lower levels of these proteins. Conclusions Collectively, these results show that miR-122 modulates Gln metabolism both in vitro and in vivo, implicating the therapeutic potential of miR-122 in HCCs that exhibit relatively high GLS levels. Highlights • miR-122, the most abundant liver specific microRNA and a potent tumor suppressor, regulates glutamine metabolism. • SIRM analysis showed enhanced glutaminolysis and impeded gluconeogenesis in the livers of miR-122 KO mice. • Gls, a key enzyme involved in glutaminolysis and a miR-122 target is upregulated in miR-122 KO livers. • Ectopic miR-122 expression suppressed glutaminolysis but enhanced gluconeogenesis in a glutamine dependent HCC cell line. • Expression of MIR-122 negatively correlated with that of GLS in human primary HCCs. |
| Databáze: | OpenAIRE |
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